I'm in too, live localy but have never done it, Ive heard it's good for PB's and it's chipped so you get an accurate time, I'm thinking of doing Manchester but havn't commited yet, as I;ve missed a few long runs, if a manage to get a couple of long ones in I'll probs do it! Good tip about the parking!
My mates have just done Silverstone today, that looks like a fast one too, looked pretty hot, a lot of dodgy stomachs apparently!